Mr Scott said: "The SNP's decision to politicise this year's Highland Show is regrettable.

"Taxpayers' money is being used to give a nationalist a political platform to rubbish the UK.

"The Highland Show should be a platform for Scotland's livestock and food - not for constitutional politics."

Mr Lochhead said the event was a fitting venue for outlining what independence could mean for rural communities.

He said: "As Rural Affairs Secretary I have worked hard to use the powers of devolution to drive forward our ambitions for rural Scotland, for its communities and its industries.

"But we will be able to do much more with the powers which independence brings.

"I firmly believe that Scotland's true potential has yet to be realised and that's particularly true in rural Scotland, where we have fantastic assets and yet, too often, find ourselves unable to harness their full potential because of the limitations of devolution.

"The Royal Highland Show is a major highlight of the rural calendar and I believe it's a fitting venue for us to outline our vision for what independence could mean for rural Scotland."

Responding to Mr Scott's comments, a spokesman for Mr Lochhead said: "This is utter hypocrisy from the Liberal Democrats given the No campaign have already announced that they will be campaigning at the Royal Highland Show.

"Indeed, Tavish Scott's party colleague George Lyon was involved in making that announcement. What's more, during his visit to last year's show the then UK farming minister, Jim Paice, spoke about the referendum.

"It is clear that many farmers are interested to hear about the opportunities that independence will bring for the industry and for rural Scotland, and it is right that Mr Lochhead sets these out at the nation's main agricultural gathering."

Mr Lyon, Lib Dem MEP for Scotland, has announced the launch of the Rural Better Together campaign at the show.